| 摘要 |
PURPOSE:To prevent the decrease in an input power factor and to improve the accuracy, by turning on a phase controller during the preceding phase of a half cycle of an AC power supply. CONSTITUTION:A controller 5 outputs a rectangular signal until both input signals are coincident with each other in a comparator 10. Since a phase controller 4 is turned on during the preceding phase period at a half cycle of the AC power supply 1, a voltage across a load 2 rises together with the AC power supply voltage and a voltage corresponding to the load 2 is integrated at an integration circuit 8. The output of the integration circuit 8 is compared with a reference voltage at the comparator 10 via a synchronizing circuit 9. Since the comparator 10 outputs a signal when the both inputs are coincident with each other, the phase comparator 4 is turned off. The operation is repeated for each half cycle of the AC power supply to keep the supply voltage to the load 2 to a set value. |
